Aerodigestive tract tumors have been hypothesized to represent a "field cancerization" process whereby a whole field is exposed to carcinogenic insult, accumulates genetic damage, and is at increased risk for proceeding through a multistep process of tumor development. The purpose of this proposal is to examine the hypothesis of "field cancerization" at the cellular and molecular levels to identify probes which can be used to characterize the multistep tumorigenesis process in the aerodigestive tract. The information gained from these initial studies will then be utilized to assess risk of malignancy in the aerodigestive tract (in individuals at risk for tumor development) as well as to determine the effect of chemoproventive treatment on these cellular parameters. Using surgically resected tumor and normal tissue obtained from individuals with primary head and neck tumors and premalignant lesions (leukoplakia), we propose to identify cytogenetic, immunocytochemical, and molecular markers that can be utilized to identify genotypic and phenotypic changes associated with tumorigenesis. We will then examine adjacent and distant "normal" tissue, in and out of the field at risk, for the degree of genetic alteration as well as for the degree of dysregulation of proliferation and differentiation (i.e. characterization of the field). Hypothetically, one would expect that individuals with head and neck primaries who exhibit increased genetic and phenotypic alterations in their normal tissue would be at increased risk for the development of a second primary. Similarly, those individuals exhibiting increased alterations in premalignant tissue (e.g. leukoplakia) might be expected to be at increased risk for developing oral cancer. These hypotheses will be tested first in a retrospective fashion by examining archival tumor and normal tissue specimens of individuals previously resected for primary head and neck tumors who have or have not subsequently developed a second primary. During the fourth and fifth years, the informative immunocytochemical and molecular probes will be utilized to examine tissues obtained prospectively from patients entered at M.D. Anderson Cancer Center onto the clinical protocols described in Projects 1 and 3 to determine the validity of the findings obtained from retrospective studies as well as to determine the effect of chemopreventive treatment on the expression of these markers in the tissue at risk.